As an apparatus for transporting a relatively small amount of liquid, a tube pump configured to move a roller pressing a tube along the tube and thereby to transport liquid in the tube by a peristaltic motion of the tube has been widely used, as described, for example, in U.S. Pat. No. 5,356,267 (hereafter, referred to as patent document #1).
FIG. 10 is a side cross section of a conventional tube pump. As shown in FIG. 10, a tube pump 201 includes a drive motor 210, a gear box 220 and a pump main body 300. A rotation shaft 211 of the drive motor 210 is connected to the gear box 220. The gear box 220 transmits a rotational motion of the drive shaft 211 to an output shaft 221 of the gear box 220 while decelerating the rotational motion of the rotation shaft 211.
The pump main body 300 includes a cap 310, a rotor 320 and a base 340. The cap 310 includes a cylindrical inner surface 311. A tube 360 of the tube pump 201 is arranged along the inner surface 311 of the cap 310.
The rotor 320 includes a rotor main body 321, a roller 322 and a roller pressure member 323. The rotor main body 321 includes a circular plate 321g and a main support shaft 321f extending from the central part of the circular plate 321g to the cap 310. The roller pressure member 323 is a member having a shape of a circular plate and is arranged on the cap 310 side with respect to the rotor main body 321. The roller pressure member 323 holds the roller 322 between the rotor main body and the roller pressure member 323. The rotor 321 is supported to be rotatable with respect to the cap 310, and is configured such that the roller 322 rotates along the inner surface 311 of the cap 310 by rotating the rotor 320. When the rotor 320 rotates, the tube 360 is pressed between the roller 322 and the inner surface 311 of the cap 310 to produce a peristaltic motion and thereby the liquid in the tube 360 is transported.
The base 340 is fixed to the gear box 220 with a bolt (not shown). The cap 310 is detachably attachable to the base 340. When the cap 310 accommodating the tube 360 and the rotor 320 is attached to the base 340, the output shaft of the gear box 220 engages with the rotor main body 321, and it becomes possible to rotate the rotor 320 by driving the drive motor 210.
In a tube pump in which liquid in a tube is transported by moving a roller, which presses a flexible tube to be a flat shape, along the tube, sometimes the tube is pulled in the moving direction of the roller by being pressed by the roller. If pulling-in of the tube occurs, the extra length of the upper side tube gradually decreases, and thereby it becomes necessary to periodically conduct a re-stretching work for the tube. Therefore, a tube fixing member for fixing the upstream part and/or the downstream part of the tube to the tube pump main body is used. Japanese Patent Provisional Publication No. 2007-198150A (hereafter, referred to as patent document #2) discloses a tube pump which uses a tube fixing member (a holder 4d) formed by bending a wire in a gate shape. In the tube pump disclosed in patent document #2, two circular holes are formed in a front surface of a main body housing which accommodates a drive motor, and a tube is fixed between the tube fixing member and the main body housing by inserting the both ends of the tube fixing member into the two circular holes. Regarding the tube fixing member of the patent document #2, the number components is small (configured by a single component), and the fixing/releasing of the tube can be achieved by insertion or drawing (i.e., a single step) of the tube fixing member. Therefore, the tube fixing member is excellent in regard to the part cost and the workability.